1. Field of the Invention
The present invention relates to a container for accommodating a powder and, more particularly, to a toner accommodating container which is used as it is loaded as a unit in an electrophotographic image forming apparatus such as a copying machine or printer.
2. Description of the Related Art
A method which allows the user to supply toner to an image forming apparatus such as an electrophotographic image forming apparatus includes a toner cartridge type with which a toner container is loaded as a unit in the image forming apparatus, and various other types with which a container is opened, and the toner in it is supplied to the apparatus. These toner accommodating containers are designed such that the toner will not contaminate the user""s hands and the interior of the image forming apparatus when it is supplied by the user.
In recent years, a used toner container is collected, and the collected toner is filled with toner and is shipped and distributed again. A resin-made recyclable container which will not deform or break easily is becoming the mainstream. A resin-made container has a good size stability and sealing performance, so that the toner filled in it is less likely to spill from it.
As the accommodating container has a high airtightness, after it is filled with toner at the factory, it maintains the original atmospheric pressure and atmosphere under which the toner has been filled. Hence, the pressure in the container sometimes becomes higher than the external atmospheric pressure due to a temperature rise or the like. When such a container is opened, sometimes the toner in it spurts out due to the pressure difference, and the spurting toner powder contaminates the user or the apparatus. This problem annoys the user who exchanges the toner cartridge when the pressure in the container is high as in a hot summer day.
Among various types of powders and granular materials, some food powder such as a powder which is made from coffee beans or used to prepare instant soda water produces a gas while it is stored. Such a gas produced from the stored powder or granular material must be discharged outside the container. Otherwise, the interior of the container expands to break the container, thus impairing the commercial value as the commodity of the stored powder or granular material product itself.
In view of these problems, a method has been proposed with which an air permeable film or vent valve is attached to the container so that the internal pressure of the container is decreased. However, a cost increase accompanying addition of a new component and an increase in number of steps cannot be avoided.
When a means for not causing a pressure difference between the interior and exterior of the container is provided to the container, the accommodated powder product is set under such conditions that it is easily exposed to the influence of the outer atmosphere over a long period of time. This is not preferable in terms of keeping the quality of the product over a long period of time. For example, if the powder product is toner for electrophotography, it is adversely affected by the outer atmosphere and its charging performance changes undesirably. When a carriage accommodating such toner is loaded in the image forming apparatus, if the charging performance of the toner changes, a target image quality may not be obtained. When the powder product is food such as a juice powder, its quality may degrade by oxidation, and its taste may change undesirably.
Regarding a highly airtight resin-made container for accommodating a powder such as toner, a technique has not been established yet that solves the pressure difference occurring between the interior and exterior of the container while maintaining the quality of the product in the container over a long period of time, so that spurt of the powder upon opening the container is prevented.
The present invention has been made in order to solve the above problems, and has for its object to provide a powder accommodating container with which contamination by powder does not occur and a toner accommodating container with which toner contamination does not occur, in which when a pressure difference occurs between the interior and exterior of the container, an excessive gas in the container is released outside, so that the pressure difference between the interior and exterior of the container is solved gently, and spurt of the powder such as toner is prevented during opening the container.
It is another object of the present invention to provide an economical powder accommodating container and toner accommodating container with which even when a means for solving the pressure difference between the interior and exterior of the container is provided, the accommodated powder product maintains a target quality over a long period of time, and the number of components and the number of steps do not increase in the manufacturing process of the container.
In order to achieve the above objects, the inventors of the present invention conducted examinations repeatedly, and discovered that the above objects can be achieved by a technique according to any one aspect of the following arrangements.
First Aspect: a powder accommodating container having at least one engaging portion between a container main body and an accessory component to be mounted on the container main body, wherein the container comprises releasing means for releasing a gas in the container outside the container.
Second Aspect: a powder accommodating container according to the first aspect, wherein the releasing means is formed in the engaging portion.
Third Aspect: a toner accommodating container having at least one engaging portion between a container main body and an accessory component to be mounted on the container main body, wherein the container comprises releasing means for releasing a gas in the container outside the container.
Fourth Aspect: a toner accommodating container according to the third aspect, wherein the releasing means is formed in the engaging portion.
Fifth Aspect: a toner accommodating container according to the third and fourth aspects, wherein the releasing means releases the gas in the toner accommodating container outside the container when a pressure difference between an interior and exterior of the container exceeds a predetermined value.
Sixth Aspect: a toner accommodating container according to the fifth aspect, wherein the releasing means releases the gas in the toner accommodating container outside the container when the pressure difference between the interior and exterior thereof exceeds 3.5 kPa.
Seventh Aspect: a toner accommodating container according to the third to sixth aspects, wherein the releasing means is a gas releasing groove formed by providing a surface of a member that constitutes the toner accommodating container with a plural and continued fine notches.
Eighth Aspect: a toner accommodating container according to the seventh aspect, wherein a width or depth of each of the notches that constitutes the gas releasing groove is larger than a particle size of toner particles to be accommodated in the toner accommodating container.
Ninth Aspect: a toner accommodating container according to the eighth aspect, wherein a depth of each of the notches that constitutes the gas releasing groove is in a range of 15 xcexcm to 100 xcexcm (both inclusive).
According to the present invention, in a powder or toner accommodating container placed in an atmosphere, e.g., in a high temperature, where a pressure difference occurs between an interior and exterior of the container, a gas releasing means is provided for releasing an excessive gas in the container outside gently and gradually when the pressure difference between the interior and exterior of the container exceeds a predetermined value. Thus, the pressure difference between the interior and exterior of the container is eliminated gently, so that powder spurt upon opening the container can be prevented. This enables to provide a powder accommodating container which does not cause contamination by the powder and a toner accommodating container which does not cause contamination with the toner.
The gas is released through the gas releasing means only when the pressure difference between the interior and exterior of the container exceeds the predetermined value, so that the air-tightness in the container is held. This enables to provide a powder accommodating container and toner accommodating container with which a powder product accommodated in it can maintain a desired quality over a long period of time.
When an improved molding die is used, a gas releasing means for eliminating the pressure difference between the interior and exterior of the container is provided. This enables to provide an economical powder accommodating container and toner accommodating container which do not increase the number of components or the number of steps in the manufacturing process of the container.
The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which a preferred embodiment incorporating the principle of the present invention is shown by way of illustrative examples.